Not Applicable
Not Applicable
1. Field of the Invention
The present invention relates to a golf club striking plate. More specifically, the present invention relates to a golf club striking plate having means for vibration attenuation.
2. Description of the Related Art
Present golf clubs have repositioned weight in order to lower the center of gravity for better performance. This repositioning of weight has for the most part attempted to thin the crown and striking plate of the golf club while precisely placing the weight in the sole of the golf club. However, thinning the striking plate too much may lead to failure of the golf club.
When the striking plate impacts a golf ball during a swing, large impact forces (in excess of 2000 pounds) are produced thereby loading the striking plate. In the relatively thin striking plates of hollow metal woods and cavity-back irons, these forces tend to produce large internal stresses in the striking plate. These internal stresses often cause catastrophic material cracking which leads to failure of the club head.
Computational and experimental studies on hollow metal woods and cavity-backed irons have demonstrated that such catastrophic material cracking most often occurs at impact points on the striking plate. These impact points require added strength to prevent club head failure.
In designing golf club heads, the striking plate must be structurally adequate to withstand large repeated forces such as those associated with impacting a golf ball at high speeds. Such structural adequacy may be achieved by increasing the striking plate stiffness so that the stress levels are below the critical stress levels of the material used in the striking plate. Typically, for metal woods, the striking plates are stiffened by uniformly increasing the thickness of the striking plate and/or by adding one or more ribs to the interior surface of the striking plate.
Uniformly increasing the thickness of the striking plate portion typically requires the addition of large amounts of material to adequately reduce the stress sufficient to prevent impact and/or fatigue cracking. However, the addition of such a large amount of material to a striking plate generally adversely affects the performance of the golf club.
One of the first patents to disclose variable face thickness was U.S. Pat. No. 5,318,300 to Schmidt et al., for a Metal Wood Golf Club With Variable Faceplate Thickness which was filed on Nov. 2, 1992. Schmidt et al discloses thickening the faceplate to prevent cracking.
A further disclosure of variable face thickness is disclosed in U.S. Pat. No. 5,830,084 to Kosmatka for a Contoured Golf Club Face which was filed on Oct. 23, 1996. Kosmatka addresses contouring the face to thicken certain regions while thinning other regions depending on the stress load experienced by such regions. Kosmatka also discloses a method for designing a face plate according to measured stress levels experienced during impact with a golf ball. Kosmatka, U.S. Pat. No. 5,971,868 for a Contoured Back Surface Of Golf Club Face, filed on Nov. 18, 1997, discloses similar contouring for an iron.
A more recent disclosure is Noble et al., U.S. Pat. No. 5,954,596, for a Golf Club Head With Reinforced Front Wall, which was filed on Dec. 4, 1997. The Noble et al. patent discloses a face plate with the thickness portion at the geometric center, and gradually decreasing toward the top and bottom, and the sole and heel. The top and bottom ends along a line through geometric center have the same thickness, and the heel and sole ends along a line through geometric center have the same thickness.
Other references make partial disclosure of varying face thickness. One example is FIG. 8 of U.S. Pat. No. 5,505,453 which illustrates an interior surface of a face with a bulging center and decreasing thickness towards the heel and sole ends, similar to Noble et al. patent. Another example is FIGS. 4C and 4D of U.S. Pat. No. 5,346,216 which discloses a bulging center that decreases in thickness toward the heel and sole ends, and the top and bottom end of the face, similar to Noble et al. patent.
Hutin et al., U.S. Pat. No. 5,316,298, for a Golf Club Head Having Vibration Damping Means, filed originally in France in 1992, discloses the use of a vibration damper on a golf club head. The main object of the Hutin patent is to attenuate the vibrations during impact with a golf ball. Hutin does not address performance, and the thickness of the striking plate. The Hutin patent discloses using a rigid plate, preferably composed of aluminum, which is attached to the interior surface by a visco-elastic material.
However, thinning of the face, either uniformly or variably, may lead to undesirable localized natural frequencies that sound xe2x80x9ctinnyxe2x80x9d when the golf club impacts a golf ball. AN undesirable sound deters from the sensation that a golfer feels during a shot, especially a good shot. Thus, although high performance drivers can increase the distance that a golf ball travels after impact with a driver, the undesirable sound may neutralize this positive effect.
The present invention is directed at a golf club head having a thin striking plate that lessens the tinny noise created during impact with a golf ball. The present invention is able to accomplish this by providing a vibration attenuation means on the interior surface of the striking plate.
One aspect of the present invention is a golf club head including a body, a striking [plate and a vibration attenuation backing. The body has a crown, a sole, a heel end, a toe end and a hollow interior. The striking plate is attached to the body, and has an exterior surface and an interior surface. The striking plate also has a thickness that varies from 0.030 inch to 0.250 inch. The vibration attenuation backing is disposed on the interior surface of the striking plate within the hollow interior of the body. The combination of the striking plate and the vibration attenuation backing has a minimum thickness of at least 0.100 inch at any point between the exterior surface of the striking plate and the hollow interior.
Another aspect of the present invention is a golf club head with a body, a unitary striking plate and a means for vibration attenuation thereon. The body has a crown, a sole, a heel end and a toe end. The unitary striking plate includes a central region, a transition region, a first peripheral region and a second peripheral region. The central region has a first thickness ranging from 0.090 inch to 0.145 inch and occupying 5% to 15% of the exterior surface of a core face area. The transition region encompassing the central region and occupies 35% to 50% of the exterior surface of a core face area. The first peripheral region encompasses the transition region and occupies 40% to 55% of the exterior surface of the core face. The first peripheral region has a second thickness less than the first thickness and ranges from 0.040 inch to 0.110 inch. The transition region has a thickness that transitions from the first thickness to the second thickness. The second peripheral region encompasses the first peripheral region and has a third thickness that ranges from 0.010 inch to 0.085 inch. The vibration attenuation means is disposed on an interior surface of the striking plate within the hollow interior of the body. The vibration attenuation means has a thickness between 0.010 inch and 0.150 inch.
The vibration attenuation means may be composed of a polymer, a low density metal or a composite material. Preferably, the vibration attenuation means is composed of a material that matches either the specific compression and/or shear stiffness of the longitudinal and/or transverse wave impedance of the striking plate material.